Among emerging adults, the public health costs of alcohol use are attributable in no small part to the effects of alcohol on other behavioral risks such as aggression, unsafe sex, and driving after drinking. A growing research literature demonstrates that alcohol intoxication decreases executive cognitive control, in particular impairing the ability to inhibit prepotent behavioral responses, and these effects may contribute to an increased propensity to engage in behavioral risks. A separate literature demonstrates that there is variability across the population in acute physiological and subjective responses to the effects of alcohol, with increasing recognition that alcohol responses reflect stable, genetically influenced individual differences. Research on alcohol responses, however, has largely focused on their role in the development of alcohol use disorders at the expense of examining their contributions to behavioral outcomes associated with acute alcohol intoxication. The proposed research will test the role of alcohol responses in predicting alcohol-related behavioral risks in the natural environment. In a first study phase, moderate-to-heavy drinking emerging adults will complete a within-subject, placebo-controlled alcohol challenge in a simulated bar environment to assess subjective and physiological alcohol responses and alcohol-induced inhibitory impairment. Greater alcohol responses are expected to be associated with greater alcohol-induced impairment in the inhibition of prepotent responses. In a second phase, the same participants will report on their alcohol use, subjective alcohol responses, and other behavioral risks using Web-based daily diaries. Greater alcohol responses in the lab will prospectively predict intoxicated behavioral risks as assessed in the event-level daily diaries, controlling for event-level alcohol responses and estimated blood alcohol concentration. Finally, greater alcohol-induced inhibitory impairment is expected to mediate the association between lab-based alcohol responses and event-level behavioral risks. The findings are expected to identify the event-level behavioral effects of greater alcohol responses. This project will integrate two separate lines of research by demonstrating that greater alcohol responses exacerbate the disinhibiting effects of alcohol on behavioral risks. These results will permit the incorporation of alcohol responses into theoretical models of the effects of alcohol on behavior and will help explain why some emerging adults are more likely to engage in harmful behaviors while intoxicated relative to others. PUBLIC HEALTH RELEVANCE: Alcohol use and disorders are most prevalent among emerging adults, and the adverse public health impact of alcohol use is largely attributable to alcohol's effects on other behavioral risks (e.g., physical aggression, unsafe sexual behaviors, driving after drinking). Importantly, however, not all emerging adults engage in these harmful behaviors when intoxicated, and our understanding of the effects of alcohol on behavior remains incomplete. This application proposes research to identify a mechanism underlying individual differences in the propensity to engage in behavioral risks as a function of alcohol responses, with the ultimate goal of improving the targeting and efficiency of interventions to reduce the public health costs of emerging-adult alcohol use.